{"gene":"ADAM2","run_date":"2026-04-28T17:12:37","timeline":{"discoveries":[{"year":1995,"finding":"Mouse ADAM2 (mPH-30 beta/fertilin beta) is expressed during meiotic and post-meiotic spermatogenesis and its disintegrin domain contains a QDE sequence (instead of RGD) that mediates sperm-egg membrane binding; peptides containing QDE decrease sperm binding and fusion with zona pellucida-free eggs by ~70%.","method":"Cloning, peptide inhibition assays of sperm-egg binding and fusion","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 — multiple functional assays (binding + fusion) with specific peptide inhibition replicated across conditions","pmids":["7593287"],"is_preprint":false},{"year":1994,"finding":"The putative fusion peptide from the alpha subunit of PH-30 (fertilin/ADAM1) binds lipid membranes and induces vesicle fusion in vitro, adopting a beta-structure upon membrane binding rather than an alpha-helical conformation, indicating it functions as a bona fide fusion domain.","method":"Synthetic peptide lipid-mixing assay, circular dichroism, FTIR spectroscopy","journal":"Biochemistry","confidence":"Medium","confidence_rationale":"Tier 1 — in vitro reconstitution with biophysical validation, but concerns ADAM1 alpha subunit fusion peptide, not ADAM2 directly","pmids":["8161498"],"is_preprint":false},{"year":2000,"finding":"The terminal aspartic acid residue of the QDECD sequence in the ADAM2 disintegrin loop is critical for sperm-egg cell adhesion function; substitutions at this position dramatically reduce activity in two independent bioassays, while substitution of the first aspartic acid has virtually no effect.","method":"Point mutagenesis of disintegrin loop sequence, two independent cell-adhesion bioassays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — active-site mutagenesis with multiple functional readouts identifying specific catalytic residue","pmids":["10713078"],"is_preprint":false},{"year":2002,"finding":"ADAM2 disintegrin domain interacts with egg plasma membrane via its ECD sequence, and MLDG peptides (which perturb alpha4/alpha9 integrin-mediated interactions) significantly inhibit ADAM2 binding to eggs, implicating alpha4/alpha9 subfamily integrins as fertilin beta receptors on the egg.","method":"Peptide inhibition assays, integrin subfamily analysis","journal":"Biology of reproduction","confidence":"Medium","confidence_rationale":"Tier 3 — peptide competition assays without direct integrin binding confirmation","pmids":["11906941"],"is_preprint":false},{"year":2004,"finding":"ADAM1a/ADAM2 fertilin complex forms in the ER of testicular germ cells and is required for the appearance of ADAM3 on the sperm surface; loss of ADAM1a abolishes surface ADAM3 in sperm, but no direct interaction between the fertilin complex and ADAM3 was detected.","method":"ADAM1a knockout mouse, western blot, immunolocalization, Co-IP","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — genetic knockout with specific molecular phenotype (loss of surface ADAM3), replicated with co-immunoprecipitation","pmids":["15194697"],"is_preprint":false},{"year":2005,"finding":"In Adam2-knockout mice, ADAM3 (cyritestin) is synthesized and transits the Golgi normally but fails to reach the cell surface; ADAM2 is required for incorporation of ADAM3 into a Triton X-100 insoluble compartment on testicular sperm that functions as a sorting platform for surface trafficking.","method":"Adam2 knockout, Endoglycosidase H resistance assay, Triton X-100 fractionation, western blot","journal":"Biology of reproduction","confidence":"High","confidence_rationale":"Tier 2 — genetic KO combined with multiple biochemical fractionation methods defining trafficking step","pmids":["16014818"],"is_preprint":false},{"year":2006,"finding":"ADAM1b/ADAM2 fertilin complex on the sperm surface is not required for sperm-egg fusion; instead, the complex is required for the surface appearance of both ADAM1b and ADAM2 themselves on epididymal sperm, as ADAM1b-deficient sperm show severely reduced surface ADAM2 despite normal testicular ADAM2.","method":"ADAM1b knockout mouse, western blot, sperm-egg fusion assay, flow cytometry","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — genetic knockout with specific surface vs. total protein comparison and functional fertilization assay","pmids":["16407235"],"is_preprint":false},{"year":2007,"finding":"ADAM2 and ADAM3 form a protein complex on the surface of mouse testicular germ cells and cauda epididymal sperm; the intracellular chaperone calnexin is a component of the testicular ADAM2-ADAM3 complex; association with ADAM2 is required for stability of ADAM3 in epididymal sperm.","method":"Co-immunoprecipitation, surface biotinylation, Endoglycosidase H resistance, Adam2-null mouse","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP identifying complex components plus genetic null model confirming stability role","pmids":["17439939"],"is_preprint":false},{"year":2008,"finding":"cAMP signaling during capacitation triggers a ~12-fold increase in the lateral diffusion of ADAM1/ADAM2 (fertilin) within the sperm plasma membrane, as measured by FRAP; this cAMP-induced release from diffusion constraints is established during epididymal maturation since testicular sperm show only modest increases.","method":"FRAP (fluorescence redistribution after photobleaching), dibutyryl-cAMP treatment, acrosome reaction assay","journal":"Biology of reproduction","confidence":"High","confidence_rationale":"Tier 2 — direct quantitative live-imaging measurement of protein mobility linked to capacitation signaling with pharmacological dissection","pmids":["18667756"],"is_preprint":false},{"year":2008,"finding":"ADAM2 is expressed in migrating neuroblasts in the rostral migratory stream (RMS) and is required for their directed migration to the olfactory bulb; ADAM2 KO mice have smaller olfactory bulbs, reduced neuroblast migration speed and loss of directionality; a peptide mimicking the ADAM2 disintegrin loop phenocopies the KO, implicating cell-cell interactions mediated by the disintegrin domain.","method":"ADAM2 knockout mouse, BrdU labeling in vivo, live slice imaging, RMS explant migration assay, disintegrin loop peptide inhibition","journal":"The European journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 — KO with multiple orthogonal migration assays plus peptide competition defining disintegrin domain function","pmids":["18380661"],"is_preprint":false},{"year":2009,"finding":"PCSK4 (proprotein convertase) regulates proteolytic processing of ADAM2 during sperm capacitation: PCSK4-null sperm show increased processing of a 46-kDa ADAM2 form to a 27-kDa form in a cholesterol efflux-dependent manner, linking PCSK4 to ADAM2 maturation.","method":"PCSK4-null mouse, western blot of capacitated sperm at different time points, cholesterol depletion experiments","journal":"Fertility and sterility","confidence":"Medium","confidence_rationale":"Tier 3 — genetic null model with western blot showing processing change, but mechanistic link is indirect","pmids":["19342015"],"is_preprint":false},{"year":2009,"finding":"In Macaca fascicularis (monkey), ADAM2 is synthesized as a 100 kDa precursor in testicular germ cells, processed to a 50 kDa intermediate in the epididymis, and finally to a 47 kDa form in sperm; the cysteine-rich domain of ADAM2 mediates protein-protein interactions that contribute to fertilin complex formation, as shown by Far-Western blot.","method":"Western blot, Far-Western blot, immunolocalization during spermatogenesis","journal":"Animal reproduction science","confidence":"Medium","confidence_rationale":"Tier 3 — Far-Western blot identifying domain for protein interaction, single study","pmids":["19443142"],"is_preprint":false},{"year":2010,"finding":"ADAM2 binding to mouse eggs is mediated by beta1 integrin (ITGB1), and a novel integrin heterodimer ITGA9-ITGB7 (in RPMI 8866 cells lacking ITGB1) can function as an ADAM2 binding partner, demonstrating that ITGA9 can dimerize with ITGB7 as a compensatory mechanism.","method":"Anti-integrin antibody blocking, siRNA knockdown of ITGB7, cell adhesion assays to ADAM2-coated surfaces, flow cytometry","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — antibody blocking and siRNA with functional adhesion readout, but single lab","pmids":["21060781"],"is_preprint":false},{"year":2016,"finding":"The cytoplasmic domain of mouse ADAM2 enables differential association with other ADAMs; monkey ADAM2 associates with chaperone proteins in the testis; human ADAM2 is present as a 100-kDa protein in testis but is absent from human sperm, suggesting species-specific differences in reproductive function.","method":"Western blot with species-specific antibodies, co-immunoprecipitation (monkey testis)","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP identifying chaperone association and domain mapping by western blot; single study","pmids":["27341348"],"is_preprint":false}],"current_model":"ADAM2 (fertilin beta) is a sperm surface ADAM-family protein that forms heterodimeric complexes (with ADAM1a and ADAM1b) in the ER of testicular germ cells, which are essential for trafficking ADAM2 itself and ADAM3 to the sperm surface via a Triton X-100-insoluble sorting compartment; on the sperm surface, ADAM2 interacts with ADAM3 (stabilizing it), and its disintegrin domain—acting through a critical terminal aspartic acid in the ECD/QDECD sequence—mediates sperm-egg adhesion by binding alpha4/alpha9-family integrins (including ITGB1-containing heterodimers) on the egg; lateral mobility of the ADAM1/ADAM2 complex is regulated by cAMP signaling during capacitation, and ADAM2 additionally promotes directed neuroblast migration in the rostral migratory stream through disintegrin loop-mediated cell-cell interactions."},"narrative":{"teleology":[{"year":1995,"claim":"Establishing that ADAM2's disintegrin domain directly mediates sperm–egg membrane binding via its QDE sequence resolved the long-standing question of which molecular feature of the fertilin heterodimer engages the egg.","evidence":"Cloning of mouse ADAM2 and peptide inhibition assays showing ~70% reduction in sperm–egg binding/fusion with QDE-containing peptides","pmids":["7593287"],"confidence":"High","gaps":["Identity of the egg receptor for the QDE sequence was unknown","Whether the disintegrin domain was sufficient or merely necessary was not tested","No knockout model yet available to confirm in vivo relevance"]},{"year":2000,"claim":"Pinpointing the terminal aspartic acid of the QDECD motif as the critical residue for adhesion activity resolved which position in the disintegrin loop is functionally essential.","evidence":"Site-directed mutagenesis of QDECD with two independent cell-adhesion bioassays","pmids":["10713078"],"confidence":"High","gaps":["Structural basis for how the terminal Asp contacts the integrin receptor was not determined","In vivo validation of the point mutant was lacking"]},{"year":2002,"claim":"Identification of α4/α9-family integrins as the egg-side receptors for ADAM2 narrowed the receptor specificity question left open by the QDE peptide studies.","evidence":"MLDG peptide competition assays implicating α4/α9 integrin subfamily in ADAM2–egg binding","pmids":["11906941"],"confidence":"Medium","gaps":["Direct binding to purified integrin heterodimers was not demonstrated","Relative contribution of individual α4/α9 heterodimers was unresolved"]},{"year":2004,"claim":"Demonstrating that the ADAM1a/ADAM2 complex forms in the ER and is required for ADAM3 surface appearance revealed that fertilin acts as an intracellular chaperone/trafficking platform, not solely a surface adhesion molecule.","evidence":"ADAM1a knockout mouse with loss of surface ADAM3; Co-IP and immunolocalization","pmids":["15194697"],"confidence":"High","gaps":["Whether ADAM2 directly contacts ADAM3 or acts indirectly was unknown","The sorting compartment through which ADAM3 traffics was not yet defined"]},{"year":2005,"claim":"Defining a Triton X-100-insoluble compartment as the ADAM2-dependent sorting platform for ADAM3 surface delivery established the specific trafficking step controlled by ADAM2.","evidence":"Adam2 knockout mouse with EndoH resistance and Triton X-100 fractionation showing ADAM3 reaches the Golgi but fails to enter the insoluble compartment","pmids":["16014818"],"confidence":"High","gaps":["Molecular identity of the Triton X-100-insoluble sorting compartment was not resolved","Whether other ADAMs also require this compartment was untested"]},{"year":2006,"claim":"Showing that the ADAM1b/ADAM2 surface complex is dispensable for sperm–egg fusion but required for mutual surface retention of both subunits separated the trafficking role from the fusion role of the fertilin complex.","evidence":"ADAM1b knockout mouse with sperm–egg fusion assay and flow cytometry for surface ADAM2","pmids":["16407235"],"confidence":"High","gaps":["What mediates sperm–egg fusion if not the ADAM1b/ADAM2 complex remained open","Whether residual surface ADAM2 contributed to partial fertility was unresolved"]},{"year":2007,"claim":"Reciprocal Co-IP demonstrated a direct ADAM2–ADAM3 surface complex with calnexin as a testicular component, establishing that ADAM2 directly stabilizes ADAM3 rather than acting solely through trafficking.","evidence":"Reciprocal Co-IP, surface biotinylation, and Adam2-null mouse showing ADAM3 instability","pmids":["17439939"],"confidence":"High","gaps":["Stoichiometry and structure of the ADAM2–ADAM3 complex were not determined","Role of calnexin beyond generic ER quality control was unclear"]},{"year":2008,"claim":"Two independent studies revealed that ADAM2 has functions beyond fertilization—cAMP-driven capacitation increases fertilin lateral mobility ~12-fold, and ADAM2 promotes directed neuroblast migration in the brain—broadening ADAM2's functional scope.","evidence":"FRAP measurement of ADAM1/ADAM2 diffusion under cAMP stimulation; ADAM2 KO mice with impaired RMS neuroblast migration, BrdU tracing, and disintegrin-loop peptide phenocopy","pmids":["18667756","18380661"],"confidence":"High","gaps":["Identity of the neuroblast receptor for ADAM2 disintegrin domain was not determined","Mechanism linking cAMP to release of diffusion constraints was not molecularly defined","Whether neuroblast migration requires ADAM2 complex partners (ADAM1/ADAM3) was untested"]},{"year":2010,"claim":"Demonstrating that ITGB1 mediates ADAM2 binding to eggs and that ITGA9–ITGB7 can serve as a compensatory receptor resolved the specific integrin heterodimers engaged by the ADAM2 disintegrin domain.","evidence":"Anti-integrin antibody blocking, siRNA knockdown of ITGB7, and cell adhesion assays on ADAM2-coated surfaces","pmids":["21060781"],"confidence":"Medium","gaps":["Whether ITGA9–ITGB7 operates on eggs in vivo was not established","Binding affinity and structural interface between ADAM2 and integrin heterodimers were not characterized"]},{"year":2016,"claim":"Species-comparison studies revealed that human ADAM2, unlike mouse, is absent from mature sperm, indicating fundamental species-specific differences in ADAM2 reproductive function.","evidence":"Western blot with species-specific antibodies across human, mouse, and monkey testis and sperm","pmids":["27341348"],"confidence":"Medium","gaps":["Functional consequence of ADAM2 absence from human sperm for human fertilization was not tested","Whether human sperm use an alternative adhesion mechanism was not explored"]},{"year":null,"claim":"The structural basis for ADAM2 disintegrin–integrin interaction, the molecular identity of the Triton X-100-insoluble sorting compartment, the neuroblast receptor for ADAM2, and the functional relevance of ADAM2 in human reproduction remain unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No crystal or cryo-EM structure of ADAM2 disintegrin domain bound to any integrin","Triton X-100-insoluble compartment not molecularly defined","ADAM2's role in human sperm function unclear given its absence from mature human sperm"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098631","term_label":"cell adhesion mediator activity","supporting_discovery_ids":[0,2,3,12]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[7,11]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[5,6,7,8]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[4,7]}],"pathway":[{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[0,2,5,6,7]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[4,5,6]}],"complexes":["ADAM1a/ADAM2 (fertilin ER complex)","ADAM1b/ADAM2 (fertilin surface complex)","ADAM2/ADAM3 surface complex"],"partners":["ADAM1A","ADAM1B","ADAM3","ITGB1","ITGA9","CANX","PCSK4"],"other_free_text":[]},"mechanistic_narrative":"ADAM2 (fertilin beta) is a sperm surface metalloprotease-family glycoprotein that orchestrates sperm–egg adhesion, sperm surface protein trafficking, and directed neuroblast migration through its disintegrin domain. The disintegrin loop ECD/QDECD sequence—specifically its terminal aspartic acid—mediates binding to egg integrins of the α4/α9 subfamily (including ITGB1-containing heterodimers), and peptide competition reduces sperm–egg binding and fusion by ~70% [PMID:7593287, PMID:10713078, PMID:21060781]. ADAM2 forms heterodimeric complexes with ADAM1a in the ER and with ADAM1b on the sperm surface; the ADAM1a/ADAM2 complex is required for incorporation of ADAM3 into a Triton X-100-insoluble sorting compartment that delivers ADAM3 to the sperm surface, and ADAM2 directly stabilizes ADAM3 in epididymal sperm [PMID:15194697, PMID:16014818, PMID:17439939]. Beyond reproduction, ADAM2 promotes directed migration of neuroblasts in the rostral migratory stream via disintegrin-domain-mediated cell–cell interactions, and its lateral mobility on the sperm membrane is dynamically regulated by cAMP signaling during capacitation [PMID:18380661, PMID:18667756]."},"prefetch_data":{"uniprot":{"accession":"Q99965","full_name":"Disintegrin and metalloproteinase domain-containing protein 2","aliases":["Cancer/testis antigen 15","CT15","Fertilin subunit beta","PH-30","PH30","PH30-beta"],"length_aa":735,"mass_kda":82.5,"function":"Sperm surface membrane protein that may be involved in sperm-egg plasma membrane adhesion and fusion during fertilization. Could have a direct role in sperm-zona binding or migration of sperm from the uterus into the oviduct. Interactions with egg membrane could be mediated via binding between its disintegrin-like domain to one or more integrins receptors on the egg. This is a non catalytic metalloprotease-like protein","subcellular_location":"Membrane","url":"https://www.uniprot.org/uniprotkb/Q99965/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ADAM2","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/ADAM2","total_profiled":1310},"omim":[{"mim_id":"618602","title":"ADAM METALLOPEPTIDASE DOMAIN-CONTAINING PROTEIN 32; ADAM32","url":"https://www.omim.org/entry/618602"},{"mim_id":"605548","title":"A DISINTEGRIN AND METALLOPROTEINASE DOMAIN 15; ADAM15","url":"https://www.omim.org/entry/605548"},{"mim_id":"603713","title":"A DISINTEGRIN AND METALLOPROTEINASE DOMAIN 21; ADAM21","url":"https://www.omim.org/entry/603713"},{"mim_id":"603712","title":"A DISINTEGRIN AND METALLOPROTEINASE DOMAIN 20; ADAM20","url":"https://www.omim.org/entry/603712"},{"mim_id":"601858","title":"CALMEGIN; CLGN","url":"https://www.omim.org/entry/601858"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in single","driving_tissues":[{"tissue":"testis","ntpm":35.6}],"url":"https://www.proteinatlas.org/search/ADAM2"},"hgnc":{"alias_symbol":["PH-30b","PH30","CT15"],"prev_symbol":["FTNB"]},"alphafold":{"accession":"Q99965","domains":[{"cath_id":"3.40.390.10","chopping":"179-373","consensus_level":"medium","plddt":90.3919,"start":179,"end":373},{"cath_id":"-","chopping":"476-613","consensus_level":"high","plddt":94.2753,"start":476,"end":613},{"cath_id":"2.40.128","chopping":"26-144","consensus_level":"medium","plddt":85.2788,"start":26,"end":144}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q99965","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q99965-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q99965-F1-predicted_aligned_error_v6.png","plddt_mean":81.44},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ADAM2","jax_strain_url":"https://www.jax.org/strain/search?query=ADAM2"},"sequence":{"accession":"Q99965","fasta_url":"https://rest.uniprot.org/uniprotkb/Q99965.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q99965/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q99965"}},"corpus_meta":[{"pmid":"15194697","id":"PMC_15194697","title":"Possible function of the ADAM1a/ADAM2 Fertilin complex in the appearance of ADAM3 on the sperm surface.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15194697","citation_count":161,"is_preprint":false},{"pmid":"7593287","id":"PMC_7593287","title":"Mouse sperm-egg plasma membrane interactions: analysis of roles of egg integrins and the mouse sperm homologue of PH-30 (fertilin) beta.","date":"1995","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/7593287","citation_count":135,"is_preprint":false},{"pmid":"8161498","id":"PMC_8161498","title":"Membrane interaction and conformational properties of the putative fusion peptide of PH-30, a protein active in sperm-egg fusion.","date":"1994","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/8161498","citation_count":84,"is_preprint":false},{"pmid":"16407235","id":"PMC_16407235","title":"Mouse sperm lacking ADAM1b/ADAM2 fertilin can fuse with the egg plasma membrane and effect fertilization.","date":"2006","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16407235","citation_count":68,"is_preprint":false},{"pmid":"10713078","id":"PMC_10713078","title":"Identification of key functional amino acids of the mouse fertilin beta (ADAM2) disintegrin loop for cell-cell adhesion during fertilization.","date":"2000","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/10713078","citation_count":64,"is_preprint":false},{"pmid":"11906941","id":"PMC_11906941","title":"Analysis of the roles of RGD-binding integrins, alpha(4)/alpha(9) integrins, alpha(6) integrins, and CD9 in the interaction of the fertilin beta (ADAM2) disintegrin domain with the mouse egg membrane.","date":"2002","source":"Biology of reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/11906941","citation_count":61,"is_preprint":false},{"pmid":"2567502","id":"PMC_2567502","title":"Isolation and mapping of a polymorphic DNA sequence pH30 on chromosome 4[HGM provisional no. D4S139].","date":"1989","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/2567502","citation_count":60,"is_preprint":false},{"pmid":"17439939","id":"PMC_17439939","title":"Identification of an ADAM2-ADAM3 complex on the surface of mouse testicular germ cells and cauda epididymal sperm.","date":"2007","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/17439939","citation_count":46,"is_preprint":false},{"pmid":"37258521","id":"PMC_37258521","title":"In vivo CRISPR screens reveal Serpinb9 and Adam2 as regulators of immune therapy response in lung cancer.","date":"2023","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/37258521","citation_count":34,"is_preprint":false},{"pmid":"16014818","id":"PMC_16014818","title":"Defects in secretory pathway trafficking during sperm development in Adam2 knockout mice.","date":"2005","source":"Biology of 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genetics","url":"https://pubmed.ncbi.nlm.nih.gov/14510675","citation_count":4,"is_preprint":false},{"pmid":"33936295","id":"PMC_33936295","title":"Localization and expression of ADAM2 in the dromedary camel testis, epididymis and sperm during rutting season.","date":"2021","source":"Animal reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/33936295","citation_count":2,"is_preprint":false},{"pmid":"39928278","id":"PMC_39928278","title":"Exploring miR-34a, miR-449, and ADAM2/ADAM7 Expressions as Potential Biomarkers in Male Infertility: A Combined In Silico and Experimental Approach.","date":"2025","source":"Biochemical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/39928278","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":12778,"output_tokens":3190,"usd":0.043092},"stage2":{"model":"claude-opus-4-6","input_tokens":6574,"output_tokens":2746,"usd":0.15228},"total_usd":0.195372,"stage1_batch_id":"msgbatch_01TqNM6p6FsoMBT2jzQTwKBr","stage2_batch_id":"msgbatch_01Ya473eco8sTHbvRymQaU8o","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1995,\n      \"finding\": \"Mouse ADAM2 (mPH-30 beta/fertilin beta) is expressed during meiotic and post-meiotic spermatogenesis and its disintegrin domain contains a QDE sequence (instead of RGD) that mediates sperm-egg membrane binding; peptides containing QDE decrease sperm binding and fusion with zona pellucida-free eggs by ~70%.\",\n      \"method\": \"Cloning, peptide inhibition assays of sperm-egg binding and fusion\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple functional assays (binding + fusion) with specific peptide inhibition replicated across conditions\",\n      \"pmids\": [\"7593287\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"The putative fusion peptide from the alpha subunit of PH-30 (fertilin/ADAM1) binds lipid membranes and induces vesicle fusion in vitro, adopting a beta-structure upon membrane binding rather than an alpha-helical conformation, indicating it functions as a bona fide fusion domain.\",\n      \"method\": \"Synthetic peptide lipid-mixing assay, circular dichroism, FTIR spectroscopy\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with biophysical validation, but concerns ADAM1 alpha subunit fusion peptide, not ADAM2 directly\",\n      \"pmids\": [\"8161498\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"The terminal aspartic acid residue of the QDECD sequence in the ADAM2 disintegrin loop is critical for sperm-egg cell adhesion function; substitutions at this position dramatically reduce activity in two independent bioassays, while substitution of the first aspartic acid has virtually no effect.\",\n      \"method\": \"Point mutagenesis of disintegrin loop sequence, two independent cell-adhesion bioassays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — active-site mutagenesis with multiple functional readouts identifying specific catalytic residue\",\n      \"pmids\": [\"10713078\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"ADAM2 disintegrin domain interacts with egg plasma membrane via its ECD sequence, and MLDG peptides (which perturb alpha4/alpha9 integrin-mediated interactions) significantly inhibit ADAM2 binding to eggs, implicating alpha4/alpha9 subfamily integrins as fertilin beta receptors on the egg.\",\n      \"method\": \"Peptide inhibition assays, integrin subfamily analysis\",\n      \"journal\": \"Biology of reproduction\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — peptide competition assays without direct integrin binding confirmation\",\n      \"pmids\": [\"11906941\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"ADAM1a/ADAM2 fertilin complex forms in the ER of testicular germ cells and is required for the appearance of ADAM3 on the sperm surface; loss of ADAM1a abolishes surface ADAM3 in sperm, but no direct interaction between the fertilin complex and ADAM3 was detected.\",\n      \"method\": \"ADAM1a knockout mouse, western blot, immunolocalization, Co-IP\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic knockout with specific molecular phenotype (loss of surface ADAM3), replicated with co-immunoprecipitation\",\n      \"pmids\": [\"15194697\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"In Adam2-knockout mice, ADAM3 (cyritestin) is synthesized and transits the Golgi normally but fails to reach the cell surface; ADAM2 is required for incorporation of ADAM3 into a Triton X-100 insoluble compartment on testicular sperm that functions as a sorting platform for surface trafficking.\",\n      \"method\": \"Adam2 knockout, Endoglycosidase H resistance assay, Triton X-100 fractionation, western blot\",\n      \"journal\": \"Biology of reproduction\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO combined with multiple biochemical fractionation methods defining trafficking step\",\n      \"pmids\": [\"16014818\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"ADAM1b/ADAM2 fertilin complex on the sperm surface is not required for sperm-egg fusion; instead, the complex is required for the surface appearance of both ADAM1b and ADAM2 themselves on epididymal sperm, as ADAM1b-deficient sperm show severely reduced surface ADAM2 despite normal testicular ADAM2.\",\n      \"method\": \"ADAM1b knockout mouse, western blot, sperm-egg fusion assay, flow cytometry\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic knockout with specific surface vs. total protein comparison and functional fertilization assay\",\n      \"pmids\": [\"16407235\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"ADAM2 and ADAM3 form a protein complex on the surface of mouse testicular germ cells and cauda epididymal sperm; the intracellular chaperone calnexin is a component of the testicular ADAM2-ADAM3 complex; association with ADAM2 is required for stability of ADAM3 in epididymal sperm.\",\n      \"method\": \"Co-immunoprecipitation, surface biotinylation, Endoglycosidase H resistance, Adam2-null mouse\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP identifying complex components plus genetic null model confirming stability role\",\n      \"pmids\": [\"17439939\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"cAMP signaling during capacitation triggers a ~12-fold increase in the lateral diffusion of ADAM1/ADAM2 (fertilin) within the sperm plasma membrane, as measured by FRAP; this cAMP-induced release from diffusion constraints is established during epididymal maturation since testicular sperm show only modest increases.\",\n      \"method\": \"FRAP (fluorescence redistribution after photobleaching), dibutyryl-cAMP treatment, acrosome reaction assay\",\n      \"journal\": \"Biology of reproduction\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct quantitative live-imaging measurement of protein mobility linked to capacitation signaling with pharmacological dissection\",\n      \"pmids\": [\"18667756\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"ADAM2 is expressed in migrating neuroblasts in the rostral migratory stream (RMS) and is required for their directed migration to the olfactory bulb; ADAM2 KO mice have smaller olfactory bulbs, reduced neuroblast migration speed and loss of directionality; a peptide mimicking the ADAM2 disintegrin loop phenocopies the KO, implicating cell-cell interactions mediated by the disintegrin domain.\",\n      \"method\": \"ADAM2 knockout mouse, BrdU labeling in vivo, live slice imaging, RMS explant migration assay, disintegrin loop peptide inhibition\",\n      \"journal\": \"The European journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO with multiple orthogonal migration assays plus peptide competition defining disintegrin domain function\",\n      \"pmids\": [\"18380661\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"PCSK4 (proprotein convertase) regulates proteolytic processing of ADAM2 during sperm capacitation: PCSK4-null sperm show increased processing of a 46-kDa ADAM2 form to a 27-kDa form in a cholesterol efflux-dependent manner, linking PCSK4 to ADAM2 maturation.\",\n      \"method\": \"PCSK4-null mouse, western blot of capacitated sperm at different time points, cholesterol depletion experiments\",\n      \"journal\": \"Fertility and sterility\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — genetic null model with western blot showing processing change, but mechanistic link is indirect\",\n      \"pmids\": [\"19342015\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"In Macaca fascicularis (monkey), ADAM2 is synthesized as a 100 kDa precursor in testicular germ cells, processed to a 50 kDa intermediate in the epididymis, and finally to a 47 kDa form in sperm; the cysteine-rich domain of ADAM2 mediates protein-protein interactions that contribute to fertilin complex formation, as shown by Far-Western blot.\",\n      \"method\": \"Western blot, Far-Western blot, immunolocalization during spermatogenesis\",\n      \"journal\": \"Animal reproduction science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Far-Western blot identifying domain for protein interaction, single study\",\n      \"pmids\": [\"19443142\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"ADAM2 binding to mouse eggs is mediated by beta1 integrin (ITGB1), and a novel integrin heterodimer ITGA9-ITGB7 (in RPMI 8866 cells lacking ITGB1) can function as an ADAM2 binding partner, demonstrating that ITGA9 can dimerize with ITGB7 as a compensatory mechanism.\",\n      \"method\": \"Anti-integrin antibody blocking, siRNA knockdown of ITGB7, cell adhesion assays to ADAM2-coated surfaces, flow cytometry\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — antibody blocking and siRNA with functional adhesion readout, but single lab\",\n      \"pmids\": [\"21060781\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The cytoplasmic domain of mouse ADAM2 enables differential association with other ADAMs; monkey ADAM2 associates with chaperone proteins in the testis; human ADAM2 is present as a 100-kDa protein in testis but is absent from human sperm, suggesting species-specific differences in reproductive function.\",\n      \"method\": \"Western blot with species-specific antibodies, co-immunoprecipitation (monkey testis)\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP identifying chaperone association and domain mapping by western blot; single study\",\n      \"pmids\": [\"27341348\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ADAM2 (fertilin beta) is a sperm surface ADAM-family protein that forms heterodimeric complexes (with ADAM1a and ADAM1b) in the ER of testicular germ cells, which are essential for trafficking ADAM2 itself and ADAM3 to the sperm surface via a Triton X-100-insoluble sorting compartment; on the sperm surface, ADAM2 interacts with ADAM3 (stabilizing it), and its disintegrin domain—acting through a critical terminal aspartic acid in the ECD/QDECD sequence—mediates sperm-egg adhesion by binding alpha4/alpha9-family integrins (including ITGB1-containing heterodimers) on the egg; lateral mobility of the ADAM1/ADAM2 complex is regulated by cAMP signaling during capacitation, and ADAM2 additionally promotes directed neuroblast migration in the rostral migratory stream through disintegrin loop-mediated cell-cell interactions.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"ADAM2 (fertilin beta) is a sperm surface metalloprotease-family glycoprotein that orchestrates sperm–egg adhesion, sperm surface protein trafficking, and directed neuroblast migration through its disintegrin domain. The disintegrin loop ECD/QDECD sequence—specifically its terminal aspartic acid—mediates binding to egg integrins of the α4/α9 subfamily (including ITGB1-containing heterodimers), and peptide competition reduces sperm–egg binding and fusion by ~70% [PMID:7593287, PMID:10713078, PMID:21060781]. ADAM2 forms heterodimeric complexes with ADAM1a in the ER and with ADAM1b on the sperm surface; the ADAM1a/ADAM2 complex is required for incorporation of ADAM3 into a Triton X-100-insoluble sorting compartment that delivers ADAM3 to the sperm surface, and ADAM2 directly stabilizes ADAM3 in epididymal sperm [PMID:15194697, PMID:16014818, PMID:17439939]. Beyond reproduction, ADAM2 promotes directed migration of neuroblasts in the rostral migratory stream via disintegrin-domain-mediated cell–cell interactions, and its lateral mobility on the sperm membrane is dynamically regulated by cAMP signaling during capacitation [PMID:18380661, PMID:18667756].\",\n  \"teleology\": [\n    {\n      \"year\": 1995,\n      \"claim\": \"Establishing that ADAM2's disintegrin domain directly mediates sperm–egg membrane binding via its QDE sequence resolved the long-standing question of which molecular feature of the fertilin heterodimer engages the egg.\",\n      \"evidence\": \"Cloning of mouse ADAM2 and peptide inhibition assays showing ~70% reduction in sperm–egg binding/fusion with QDE-containing peptides\",\n      \"pmids\": [\"7593287\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Identity of the egg receptor for the QDE sequence was unknown\",\n        \"Whether the disintegrin domain was sufficient or merely necessary was not tested\",\n        \"No knockout model yet available to confirm in vivo relevance\"\n      ]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Pinpointing the terminal aspartic acid of the QDECD motif as the critical residue for adhesion activity resolved which position in the disintegrin loop is functionally essential.\",\n      \"evidence\": \"Site-directed mutagenesis of QDECD with two independent cell-adhesion bioassays\",\n      \"pmids\": [\"10713078\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structural basis for how the terminal Asp contacts the integrin receptor was not determined\",\n        \"In vivo validation of the point mutant was lacking\"\n      ]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Identification of α4/α9-family integrins as the egg-side receptors for ADAM2 narrowed the receptor specificity question left open by the QDE peptide studies.\",\n      \"evidence\": \"MLDG peptide competition assays implicating α4/α9 integrin subfamily in ADAM2–egg binding\",\n      \"pmids\": [\"11906941\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct binding to purified integrin heterodimers was not demonstrated\",\n        \"Relative contribution of individual α4/α9 heterodimers was unresolved\"\n      ]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Demonstrating that the ADAM1a/ADAM2 complex forms in the ER and is required for ADAM3 surface appearance revealed that fertilin acts as an intracellular chaperone/trafficking platform, not solely a surface adhesion molecule.\",\n      \"evidence\": \"ADAM1a knockout mouse with loss of surface ADAM3; Co-IP and immunolocalization\",\n      \"pmids\": [\"15194697\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether ADAM2 directly contacts ADAM3 or acts indirectly was unknown\",\n        \"The sorting compartment through which ADAM3 traffics was not yet defined\"\n      ]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Defining a Triton X-100-insoluble compartment as the ADAM2-dependent sorting platform for ADAM3 surface delivery established the specific trafficking step controlled by ADAM2.\",\n      \"evidence\": \"Adam2 knockout mouse with EndoH resistance and Triton X-100 fractionation showing ADAM3 reaches the Golgi but fails to enter the insoluble compartment\",\n      \"pmids\": [\"16014818\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Molecular identity of the Triton X-100-insoluble sorting compartment was not resolved\",\n        \"Whether other ADAMs also require this compartment was untested\"\n      ]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Showing that the ADAM1b/ADAM2 surface complex is dispensable for sperm–egg fusion but required for mutual surface retention of both subunits separated the trafficking role from the fusion role of the fertilin complex.\",\n      \"evidence\": \"ADAM1b knockout mouse with sperm–egg fusion assay and flow cytometry for surface ADAM2\",\n      \"pmids\": [\"16407235\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"What mediates sperm–egg fusion if not the ADAM1b/ADAM2 complex remained open\",\n        \"Whether residual surface ADAM2 contributed to partial fertility was unresolved\"\n      ]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Reciprocal Co-IP demonstrated a direct ADAM2–ADAM3 surface complex with calnexin as a testicular component, establishing that ADAM2 directly stabilizes ADAM3 rather than acting solely through trafficking.\",\n      \"evidence\": \"Reciprocal Co-IP, surface biotinylation, and Adam2-null mouse showing ADAM3 instability\",\n      \"pmids\": [\"17439939\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Stoichiometry and structure of the ADAM2–ADAM3 complex were not determined\",\n        \"Role of calnexin beyond generic ER quality control was unclear\"\n      ]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Two independent studies revealed that ADAM2 has functions beyond fertilization—cAMP-driven capacitation increases fertilin lateral mobility ~12-fold, and ADAM2 promotes directed neuroblast migration in the brain—broadening ADAM2's functional scope.\",\n      \"evidence\": \"FRAP measurement of ADAM1/ADAM2 diffusion under cAMP stimulation; ADAM2 KO mice with impaired RMS neuroblast migration, BrdU tracing, and disintegrin-loop peptide phenocopy\",\n      \"pmids\": [\"18667756\", \"18380661\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Identity of the neuroblast receptor for ADAM2 disintegrin domain was not determined\",\n        \"Mechanism linking cAMP to release of diffusion constraints was not molecularly defined\",\n        \"Whether neuroblast migration requires ADAM2 complex partners (ADAM1/ADAM3) was untested\"\n      ]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Demonstrating that ITGB1 mediates ADAM2 binding to eggs and that ITGA9–ITGB7 can serve as a compensatory receptor resolved the specific integrin heterodimers engaged by the ADAM2 disintegrin domain.\",\n      \"evidence\": \"Anti-integrin antibody blocking, siRNA knockdown of ITGB7, and cell adhesion assays on ADAM2-coated surfaces\",\n      \"pmids\": [\"21060781\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether ITGA9–ITGB7 operates on eggs in vivo was not established\",\n        \"Binding affinity and structural interface between ADAM2 and integrin heterodimers were not characterized\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Species-comparison studies revealed that human ADAM2, unlike mouse, is absent from mature sperm, indicating fundamental species-specific differences in ADAM2 reproductive function.\",\n      \"evidence\": \"Western blot with species-specific antibodies across human, mouse, and monkey testis and sperm\",\n      \"pmids\": [\"27341348\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Functional consequence of ADAM2 absence from human sperm for human fertilization was not tested\",\n        \"Whether human sperm use an alternative adhesion mechanism was not explored\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The structural basis for ADAM2 disintegrin–integrin interaction, the molecular identity of the Triton X-100-insoluble sorting compartment, the neuroblast receptor for ADAM2, and the functional relevance of ADAM2 in human reproduction remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No crystal or cryo-EM structure of ADAM2 disintegrin domain bound to any integrin\",\n        \"Triton X-100-insoluble compartment not molecularly defined\",\n        \"ADAM2's role in human sperm function unclear given its absence from mature human sperm\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098631\", \"supporting_discovery_ids\": [0, 2, 3, 12]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [7, 11]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [5, 6, 7, 8]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [4, 7]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [0, 2, 5, 6, 7]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [4, 5, 6]}\n    ],\n    \"complexes\": [\n      \"ADAM1a/ADAM2 (fertilin ER complex)\",\n      \"ADAM1b/ADAM2 (fertilin surface complex)\",\n      \"ADAM2/ADAM3 surface complex\"\n    ],\n    \"partners\": [\n      \"ADAM1A\",\n      \"ADAM1B\",\n      \"ADAM3\",\n      \"ITGB1\",\n      \"ITGA9\",\n      \"CANX\",\n      \"PCSK4\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}